The present invention relates to devices that dispense air treatment chemicals (“actives”) from a substrate using the heat of a candle to drive the dispensing. More particularly, the invention relates to such devices that dispense the active over a prolonged period in a relatively consistent manner that provides effective coverage throughout an area such as an outdoor patio.
A variety of devices are known for dispensing volatilizable air treatment chemicals such as pest control materials (e.g., insecticides, insect repellants, or insect growth control regulators), air scents or deodorizers (e.g., masks), allergen control ingredients, disinfectants, sanitizers or other materials. In some of these devices the air treatment chemical is mixed with candle wax and is dispensed during candle burning (where the chemical is released primarily from the heated wax surrounding the wick). While this is a common technique for dispensing a variety of fragrances, typically it has been less successful when dispensing certain particularly desirable pest control materials.
Attempts have been made to use heat from a candle to distribute air treatment chemicals from an adjacent impregnated pad surface. See e.g., U.S. Pat. Nos. 4,781,895, 7,138,130 and 8,047,837. However, it is difficult to design such devices to work over a four hour, six hour or even longer period (four to six hours being a typical period for a dinner party or picnic) while consistently distributing enough chemical to be effective in a large area throughout that period.
Some attempts have been made to use electrical heaters to drive air treatment chemicals in a more controlled manner from a substrate or reservoir. See U.S. Pat. No. 7,820,188. However, such systems required structures to generate, store, and/or accommodate electrical power, which increases the cost of the device.
U.S. patent application publication 2012/0251962 taught a trapeze-like structure for lowering a candle into a glass chimney, but was not directed to dispensing a volatizable air treatment chemical.
Thus, a need exists for low cost air treatment chemical dispensers where heat drives an air treatment chemical off of a carrier substrate in a way which provides prolonged useful life and capability of treating a large area.